I'll keep this very brief because lets face it, we have mods that do this, I just feel its something that should be officially done, especially given it would allow "balancing" to be accounted for. If anyone really wonders why I say this its largely because of some of the new Extinction creatures which are very powerful are are breedable, that and I think it would be good for QoL, it would after all mean All Dino's get Baby and growing up states
So yeah the basic premise is this, create official breeding methods for ALL Dino's currently implemented into the game except perhaps the Titans (I'll leave that for another discussion lets get past this one first).
These conditions being more complicated depending on the DIno itself and on top of this give us the ability to choose which Dino's are/ aren't breedable. This way official servers can still restrict breeding on DIno's where required for the sake of balancing.
I'll give some examples of these below, obviously you can argue they may be too simple or difficult to implement but the basic ideas seem sound enough and just need improving upon hopefully and where I'm struggling I'll just say where I'd start for searching for the involved mechanics / conditions.
Invertebrates such as the Araneo, Arthropluera, Dung Beetle, Lymantria, Mantis, Pulmonoscorpius for example. I'm going to stick with some basic things I know about Spider and Mantis' and base my suggestion on the fact that the Females tend to like to eat the Males in a more realistic application and go for the in game application of, when a Male and Female are breeding the Male gets Health Degeneration, so you have to do something to keep the Male alive, such as heal it, equally while this is happening just for the sake of imitation you could have the Female get the relevant Buffs from eating.
Next Basilisks and Titanboa's, not gonna lie I don't know much about snakes, all I can really say is base Titanboas a bit more off actual snakes and add a more difficult element to the Basilisk.
For Robots (Scout, Enforcer and dare I say it MEK?) I'm not really sure what you could do either as they are not really Dino's I'd say you'd have to find a Versioning or Revisions system on them that replicated breeding with the end result being a New Blueprint (Maybe you have to make a station and put the Blueprints in them? It is throwing out new revisions) or maintain them not being "unbreedable" I find this one a difficult call to be honest.
Griffins are another difficult example especially when I consider the Snow Owl which uses a similar flight mechanic is just straight up breedable so I would say they have to be bred perhaps at high altitude? or depending on the mythology your going with they might need to be given a "valuable" thing to encourage them to "Nest for breeding"
Karkinos being mutated crabs makes me imagine we would have to ensure we have the correct type of environment, so temperature management and access to water would probably be on my list of conditions.
Onyc, I'm going to be lazy here and go, its a bat, it only breeds at night time.
Phoenix, another difficult one, I would opt for it has to be very hot, it can't be in the rain and perhaps for the fun of it it either has to be in an area where there is the Extreme Heatwave weather effect or its given a food if on another map such as I dunno, Fria Curry?
Piranha, dunno? Just give them it I don't know how much them being breedable would cause issues normally to be honest.
Reapers, these I really can’t think of anything for outside of us being given a way of doing what some of us already do and trapping a Reaper Queen, your kind of on your own here as far as suggestions go.
Rock Drakes I would associate with requiring Radiation so perhaps we would need to give them a unique food, or craft a structure that allows us to create an area that effectively replicates a Radiation heavy area like their nests, so a shelter with a "Radiation Generator" for example.
Rock Elementals are one of the more fun things I suppose as they are mineral based, honestly, I wouldn't even have them as Baby Rock Elemental, I'd have them as a Sand Elemental or something and when they are fully grown, they become a Rock Elemental. AS for breeding them I couldn't say I imagine you would have to give the Rock Elemental something to encourage it to replicate itself, naturally you'd need at least 2 Rock Elementals.
Wyverns, well I'm going to go back to a similar concepts to the Phoenix / Rock Drake and say we want to try to recreate some of the environmental Factors depending on the Wyvern or reply on the map having a natural weather effect so say the Super Heatwave for Fire / Poison Wyverns, the Electrical Storm for the Lightning Wyvern and Rain / Snow for the Ice variant, each of these requiring Temperature management on top of this and perhaps have a food to allow breeding on other maps where these weather effects don't exist.
All in all, you hopefully get the ideas I’m going for at a minimum even if you don’t agree with the suggesting methods or believe they can’t be implemented. I’d say they are OK starting points and again I want to reiterate that while I’m suggesting All Dino’s have the ability to breed, I also want us to be able to set which of the Dino’s that spawn on our servers are actually able to breed. That way if we don’t want people to breed Rock Drakes specifically, we can turn it off for example.
Of course, there is more than just this to consider such as Imprinting as well as what unique mechanics you might want to add to some of them as they grow up (Looks at invertebrates and Rock Elementals) and what I've suggested as mechanics are literally just that, suggestions to get ideas flowing.